1. Field of the Inventions
The inventions generally relates to video decoders, and more specifically to input video signal shaping, and even more specifically to providing constant video signal levels and improving analog-to-digital conversion accuracy.
2. Description of Related Art
There is a large surge in the use of digital video devices today. Examples include: digital televisions, LCD TVs and monitors, DVD recorders, personal video recorders, PC video cards, video capture and streaming applications, and video conferencing. In many cases, these units need to receive an analog video signal, which may be one of the composite signals, such as NTSC, PAL or SECAM; s-video; component video or RGB. It is then desirable to produce the proper digital output, such as eight or ten bit ITU-R BT 656. It is preferred that all the video decoding be done in a single chip for all of these formats. The decoder not only has to handle composite signals, which means it must be able to determine the chroma and luma values, but it also must handle vertical blanking interval (VBI) data and handle VCR signals, which may be unstable signals.
Although a number of such systems have been developed, it is always desirable to improve the output and capabilities of the particular video decoder. For example, one common problem is resolution of any analog-to-digital converters which are utilized. For manufacturing cost reasons, it is preferable that as few digital bits as possible be used, but at the same time more digital bits are desirable to improve output quality. Therefore, it is desirable to allow both fewer bits to be used in the conversion and still improve quality.